package com.news.util;
/**
* 有了记录总条数后，页面控制类；
* 根据总记录数，每页显示条数，来得到总页数;
* @author Administrator
*
*/
public class PageControler {
public int getTotalPages(int count,int pageSize){
int totalPages=0;
//如果总记录数除以每页显示条数，能够整除;
//总页数就是它们的商，否则为商+1
if(count%pageSize==0){
totalPages=count/pageSize;
}else{
totalPages=count/pageSize+1;
}
return totalPages;
}
}UserDao中的抽象方法
//通过查询获取数据表中数据总条数;
public int getCount();
//根据当前页码和页数，来分页的方法;返回User集合;
public List<User>queryUserByPage(int currentPage,int pageSize);
//UserDaoImpl实现类中的方法
/* 获得user的总个数,即要分页的总记录数
* @see com.news.dao.UserDao#getCount()
*/
@Override
public int getCount() {
Connection con=null;
Statement st=null;
ResultSet rs=null;
int count=0;
try {
con=DaoFactory.getConnection();
st=con.createStatement();
String sql="select count(*) from t_user";
rs=st.executeQuery(sql);
if(rs.next()){
count=rs.getInt(1);
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
DaoFactory.closeAll(rs, st, con);
}
return count;
}
@Override
public List<User> queryUserByPage(int currentPage, int pageSize) {
Connection con=null;
Statement st=null;
ResultSet rs=null;
List<User>users=null;
try {
con=DaoFactory.getConnection();
st=con.createStatement();
users=new ArrayList<User>();
String sql="select top "+pageSize+" * from t_user where id not in (select top "+(currentPage-1)*pageSize+" id from t_user order by id)order by id";
rs=st.executeQuery(sql);
//遍历结果集
while(rs.next()){
//从数据库中取出一条记录后，放到实体对象中;
User user=new User();
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setEmail(rs.getString("email"));
user.setAddress(rs.getString("address"));
user.setHobby(rs.getString("hobby"));
//将实体对象放入集合中;
users.add(user);
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
DaoFactory.closeAll(rs, st, con);
}
return users;
}show_user.jsp页面代码如下
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page import="com.news.dao.*,com.news.dao.impl.*,com.news.entity.*,com.news.util.*" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="https://www.ctyun.cn/portal/link.html?target=%26lt%3B%25%3DbasePath%25%26gt%3B">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<link rel="stylesheet" type="text/css" href="https://www.ctyun.cn/portal/link.html?target=css%2Fcss.css">
</head>
<body>
<table border="1" align="center">
<caption>=用户列表</caption>
<tr>
<td>编号</td>
<td>账号</td>
<td>密码</td>
<td>邮箱</td>
<td>住址</td>
<td>爱好</td>
</tr>
<%
//获取当前页码，如果获取不到，默认是第一页;
String pageIndex=request.getParameter("pageIndex");
if(pageIndex==null){
pageIndex="1";
}
int currentPage=Integer.parseInt(pageIndex);
int pageSize=4;
UserDao ud=new UserDaoImpl();
PageControler pc=new PageControler();
int count=ud.getCount();
//获得总页数;
int totalPages=pc.getTotalPages(count,pageSize);
//分页查询，得到当前页数数据;
List<User>users=ud.queryUserByPage(currentPage,pageSize);
for(int i=0;i<users.size();i++){
User user=users.get(i);
%>
<tr>
<td><%=user.getId() %></td>
<td><%=user.getUsername() %></td>
<td><%=user.getPwd() %></td>
<td><%=user.getEmail() %></td>
<td><%=user.getAddress() %></td>
<td><%=user.getHobby() %></td>
</tr>
<%
}
%>
<!-- 分页控制 -->
<tr class="altrow">
<td colspan="6">
第<%=currentPage %>页/共<%=totalPages %>页
<a href='https://www.ctyun.cn/portal/link.html?target=admin%2Fshow_user.jsp%3FpageIndex%3D%26lt%3B%25%3D1+%25%26gt%3B'>首页</a>
<%
if(currentPage>1){
%>
<a href='https://www.ctyun.cn/portal/link.html?target=admin%2Fshow_user.jsp%3FpageIndex%3D%26lt%3B%25%3DcurrentPage-1+%25%26gt%3B'>上一页||</a>
<%
}
if(currentPage<totalPages){
%>
<a href='https://www.ctyun.cn/portal/link.html?target=admin%2Fshow_user.jsp%3FpageIndex%3D%26lt%3B%25%3DcurrentPage%2B1+%25%26gt%3B'>下一页</a>||
<%} %>
<a href='https://www.ctyun.cn/portal/link.html?target=admin%2Fshow_user.jsp%3FpageIndex%3D%26lt%3B%25%3DtotalPages+%25%26gt%3B'>末页</a>
</td>
</tr>
</table>
</body>
</html>
